[Mesa-maintainers] RFC discussion using meson for Mesa

[Marek Olšák]

Hi,

What has been unpleasant for me recently is that the current build
system doesn't support parallelism very well. There are 3 areas that
can be improved:

1) Linking is single-threaded and independent files aren't compiled in
parallel with the linking. This is the biggest issue. LLVM doesn't
have this issue when built with ninja.

2) Small directories decrease CPU core utilization because there are
not enough files in that directory.

3) ./configure takes more time than alternatives.

The current build system does a decent job on dual-core and quad-core,
but not on 16-thread Ryzen or better.

Marek

On Wed, Mar 22, 2017 at 1:06 PM, Emil Velikov <emil.l.velikov at gmail.com> wrote:
> On 21 March 2017 at 18:10, Andreas Boll <andreas.boll.dev at gmail.com> wrote:
>> FYI there's a libtool performance regression which causes a slower
>> build of mesa.
>>
>> See http://harald.hoyer.xyz/2015/03/05/libtool-getting-rid-of-180000-sed-forks/
>> and https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=848864
>>
>> There are three commits [1] [2] [3] for mitigating this issue in the
>> libtool git repo since 2015
>> but unfortunately those patches haven't made it into a release yet.
>>
> Thanks for bringing this up Andreas, I'll check what's the hold up on
> their end and how we can get things going again.
> Might also try to get my distro (Arch) to use the patches, considering
> the noticeable change.
>
> -Emil
>
> libtool 2.4.2
> real    20m56.007s
> user    29m20.010s
> sys     1m5.180s
>
> libtool 2.4.6 - aka nearly 50% time increase
> real    27m58.143s
> user    37m55.500s
> sys     1m36.470s